The subject matter disclosed herein relates to a pressure relief door assembly and, more particularly, to a pressure relief door assembly for burst duct detection.
Modern aircraft, such as commercial jets, include a fuselage that is formed to define a cabin and a cockpit and which has a nose cone section and a tail section, wings extending outwardly from the fuselage and a tail at the tail section of the fuselage. Thrust for the aircraft is generated by engines that are positioned within engine nacelles and typically either attach to the undersides of the wings, or the sides of the fuselage near the rear of the plane, or are built into the tail. The engines include an air inlet, a compressor to compress inlet air, a combustor in which fuel is mixed with compressed inlet air and combusted to produce a working fluid and a turbine in which the working fluid is expanded. The engines further include an outlet through which the working fluid is exhausted to generate the thrust.
The engine nacelles may include an inner fixed structure (IFS), which generally surrounds and provides an aerodynamic fairing for the engine and certain auxiliary devices including ducts that carry fluids to and from the engine sections and auxiliary devices and to the airplane. The engine nacelles further include several structures disposed radially outwardly of the IFS, some of which help define, along with the inner fixed structure, a duct for fan bypass air in a turbofan engine. The IFS may include one or more pressure relief doors.
A failure mode of compressed air ducts associated with the engine can occur when one or more ducts bursts in a “burst duct event.” When this occurs, the pressure relief door will open automatically due to its latch being triggered to relieve overpressure in the compartment formed around the engine by the IFS to prevent structural damage. If a burst duct event does occur, the burst duct event needs to be identified so that appropriate inspections and any necessary repairs can be accomplished.
Currently, burst duct events can be identified by degraded engine performance expressed by the cockpit instruments but, since degraded engine performance expressed by the cockpit instruments does not always lead to identification of the burst duct event, a visual means of detection is often needed as a primary detection means or as a backup means. Often, a burst duct event can be detected through a visual inspection of the nacelle and the pressure relief door by identifying that the pressure relief door has unlatched and opened. However, due to the location of some pressure relief doors generally being on the upper hemisphere of the engine nacelle, if a burst duct event occurs and the pressure relief door opens during flight, the pressure relief door may return to or close to its original position due to gravity, and therefore not allow for the burst duct event to be detected from an inspection of the pressure relief door.